CH636364A5 - Process for the preparation of cold-curing, flexible foams containing urethane groups - Google Patents

Description

The present invention thus relates to a process for the production of cold-curing, flexible foams containing urethane groups by reacting at least two hydroxyl-containing polyethers with a molecular weight of 400-10,000, in which at least 10% by weight of the hydroxyl groups present are primary hydroxyl groups, and optionally , in amounts up to 50% by weight, based on the polyether, of polyesters which have 2-8 hydroxyl groups, of primary hydroxyl-free, at least two hydroxyl group-containing polyethers, polythioethers, polyacetals, polycarbonates and polyesteramides and their mixtures of molecular weight 400-10,000, with a mixture of diphenylmethane diisocyanates and oligomeric polyphenyl polymethylene polyisocyanates, which in addition up to 20 wt .-%, based on the mixture of isocyanates, aliphatic, cycloaliphatic and aromatic isocyanates different from the aromatic isocyanates mentioned and h can contain heterocyclic polyisocyanates and mixtures thereof, during the reaction optionally up to 50% by weight, based on the polyether, of 2 isocyanate-reactive compounds with a molecular weight of 32-400 having hydrogen atoms are present in the presence of blowing agents, the characterized in that the mixture of diphenylmethane diisocyanates and oligomeric polyphenylpolymethylene polyisocyanates contains 60-90% by weight of 4,4'-diphenylmethane diisocyanate and 3-30% by weight of 2,4'-diphenylmethane diisocyanate.

The reaction according to the invention is preferably carried out in the presence of catalysts and other foam auxiliaries.

The mixture of diphenylmethane diisocyanates and oligomeric polyphenyl polymethylene polyisocyanates contains in particular 10-25% by weight, preferably 10-20% by weight, of 2,4'-diphenylmethane diisocyanate.

The reaction can be carried out in the absence of foam stabilizers of the polyether polysiloxane type.

Foam molded parts with integral skin are preferably produced.

Surprisingly, the following technical advantages have been shown in the process according to the invention:

1. Due to the very fast curing of these foam systems, unusually short mold lives of 3 minutes to less than 1 minute can be achieved.

2. The rapid curing significantly reduces the susceptibility to deformation, which significantly shortens any interim storage times. Baking out the

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Molded parts after demolding are no longer necessary. Packaging of the foams is e.g. possible after 20 minutes without deformation.

The mixture of diphenylmethane diisocyanates and oligomeric polyphenyl polymethylene polyisocyanates to be used in the process according to the invention and its preparation are known per se.

Suitable starting components to be used according to the invention, optionally in amounts of at most 20% by weight, based on the poly-isocyanate mixture to be used, are aliphatic, cycloaliphatic and other aromatic and heterocyclic polyisocyanates, such as those e.g. by W. Siefken in Justus Liebigs Annalen der Chemie 562, pages 75 to 136, for example ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane-1,3 -diisocyanate, cyclohexane-1,3- and -1,4-diiso-cyanate and any mixtures of these isomers, 1-isocyanate-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (DAS 1 202 785, American Patent 3,401,190), 2,4- and 2,6-hexahydrotoluene diisocyanate and any mixtures of these isomers, hexahydro-1,3-and / or -1,4-phenylene diisocyanate, perhydro-2,4'-and / or -4,4'-diphenylmethane diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2,6-tolylene diisocyanate and any mixtures of these isomers, naphthylene-l, 5-diisocyanate, triphenylme -thane-4,4 ', 4 "-triisocyanate, m- and p-isocyanatophenylsul-fonyl-isocyanate according to the American patent 3,454,606, perchlorinated aryl polyisocyanates, as described, for example, in German patent application 1 157601 (ameri Canadian Patent 3,277,138), carbodiimide group-containing polyisocyanates as described in German Patent 1,092,007 (American Patent 3,152,162), diisocyanates as described in American Patent 3,492,330 containing allophanate groups Polyisocyanates, such as in British patent specification 994 890, Belgian patent specification 761 626 and the published Dutch patent application? 102 524, polyisocyanates containing isocyanurate groups, such as those e.g. in the American patent specification 3 001 973, in the German patent specifications 1 022789.1 222067 and 1027 394 as well as in the German laid-open specifications 1 929 034 and 2 004 048, polyisocyanates containing urethane groups, such as those e.g. in the Belgian patent specification 752 261 or in the American patent specification 3 394164, polyisocyanates containing acylated urea groups according to the German patent specification 1 230778, polyisocyanates containing biuret groups, such as those e.g. in German patent specification 1 101 394 (American patent specifications 3 124605 and 3 201 372) and in British patent specification 889 050 are described, polyisocyanates produced by telomerization reactions, such as those e.g. in US Pat. No. 3,654,106, ester group-containing polyisocyanates, such as those mentioned, for example, in British Patents 965,474 and 1,072,956, in American Pat. No. 3,567,763 and in German Pat. No. 1,231,688, are reaction products of the above-mentioned isocyanates with acetals according to German patent 1,072,385 and polyisocyanates containing polymeric fatty acid residues according to American patent 3,455,883.

It is also possible to use the distillation residues obtained in the technical production of isocyanates and having isocyanate groups, optionally dissolved in one or more of the aforementioned polyisocyanates. It is also possible to use any mixtures of the aforementioned polyisocyanates.

Monofunctional isocyanates such as propyl isocyanate, cyclohexyl isocyanate, phenyl isocyanate, toluyl isocyanate, p-chlorophenyl isocyanate can also be used.

Starting components to be used according to the invention are also polyethers having at least two hydroxyl groups with a molecular weight of 400-10,000, in particular two to eight, but preferably 2 to 4, hydroxyl groups-containing polyethers, especially those with a molecular weight of 800 to 10,000, preferably 1000 to 6000, wherein in the polyethers represent at least 10% by weight of the hydroxyl groups of primary hydroxyl groups.

These polyethers are known per se and are e.g. by polymerizing epoxides such as ethylene oxide and optionally propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with themselves, e.g. in the presence of BF3, or by the addition of these epoxides, optionally in a mixture or in succession, to starting components with reactive hydrogen atoms such as water, alcohols, ammonia or amines, e.g. Ethylene glycol, propylene glycol (1,3) or - (1,2), trimethylol propane, glycerin, 4,4'-dihydroxydiphenylpropane, aniline, ethanolamine or ethylenediamine, the (terminal) primary hydroxyl groups preferably being produced by ethylene oxide Implementation arise. Also sucrose poly ether such as e.g. described in German interpretations 1 176 358 and 1 064938 are possible according to the invention. Polyethers modified by vinyl polymers, e.g. Polymerization of styrene and acrylonitrile in the presence of polyethers (US Pat. Nos. 3,383,351,3,304,273,3,523,093, 3,110,695, German Pat. No. 1,152,536) are suitable, as are OH-containing polybutadienes.

According to the invention, optionally in addition to the polyethers in amounts up to a maximum of 50% by weight, based on polyether, of starting components to be used are furthermore 2 to 8, but preferably 2 to 4, hydroxyl-containing polyesters, of primary hydroxyl-free, at least two hydroxyl-containing polyethers, polythio ether, polyacetals, polycarbonates and polyesteramides, as are known per se for the production of homogeneous and cellular polyurethanes, of a molecular weight of 400-10,000, especially those of molecular weight 800 to 10,000, preferably 1000 to 6000.

The hydroxyl group-containing polyesters are e.g. Reaction products of polyhydric, preferably dihydric and optionally additionally trihydric alcohols with polyhydric, preferably dihydric, carboxylic acids. Instead of the free polycarbonic acids, the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof can also be used to produce the polyesters. The polycarboxylic acids can be aliphatic, cycloaliphatic, aromatic and / or heterocyclic in nature and optionally, e.g. by halogen atoms, substituted and / or unsaturated.

mentioned as examples: succinic acid, adipic acid, azelaic acid, phthalic acid, trimellitic anhydride, phthalic anhydride, Hexahydrophthalsäurean hydride, tetrachlorophthalic, Endomethylentetra-hydrophthalic, glutaric anhydride, maleic anhydride, fumaric acid, dimeric and tri-mers fatty acids such as oleic acid, optionally in a mixture with monomeric fatty acids, dimethyl terephthalate and bis-glycol terephthalate. As polyhydric alcohols are e.g. Ethylene glycol, propylene glycol (1,2) and - (1,3),

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Butylene glycol (1,4) and - (2,3), hexanediol (1,6), octanediol (1,8), neopentyl glycol, cyclohexanedimethanol (1,4-bis-hydroxymethylcyclohexane), 2-methyl-l, 3-propanediol, glycerin, trimethylolpropane, hexanetriol- (1,2,6), butanetriol- (1,2,4), trimethylolethane, pentaerythritol, quinite, mannitol and sorbitol, methylglycoside, also diethylene glycol, triethylene glycol, tetraethylene glycol , Polyethylene glycols, dipropylene glycol, polypropylene glycols, dibutylene glycol and polybutylene glycol in question. The polyesters can have a proportion of terminal carboxyl groups. Also polyester from lac-tones, e.g. e-caprolactone or hydroxycarboxylic acids, e.g. w-hydroxycaproic acid can be used.

The polyethers which may also be used in the process according to the invention and have at least two, generally two to eight, preferably two to three, hydroxyl groups (but no primary hydroxyl groups) are in particular those of the type known per se and can, for example, by polymerizing epoxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with themselves, e.g. in the presence of BF3, or by the addition of these epoxides, optionally in a mixture or in succession, to starting components with reactive hydrogen atoms such as water, alcohols, ammonia or amines, e.g. Ethylene glycol, propylene glycol (1, 3) or (1,2), trimethylolpropane, 4,4'-dihydroxy-diphenylpropane, aniline, ethanolamine or ethylenediamine. Also sucrose polyethers, e.g. described in German patent specifications 1 176358 and 1 064938 can be used in the process according to the invention. All of these polyethers contain no primary OH groups.

Among the polythioethers, the condensation products of thiodiglycol with themselves and / or with other glycols, dicarboxylic acids, formaldehyde, amino carboxylic acids or amino alcohols should be mentioned in particular. Depending on the co-components, the products are polythio ether, polythioether ester or polythioether ester amide.

As polyacetals e.g. the compounds which can be prepared from glycols, such as diethylene glycol, triethylene glycol, 4,4'-dioxethoxydiphenyldimethylmethane, hexanediol and formaldehyde. Suitable polyacetals can also be prepared by polymerizing cyclic acetals.

Particularly suitable polycarbonates containing hydroxyl groups are those of the type known per se, which, for example, by reacting diols such as propane-diol (1,3), butanediol (1,4) and / or hexanediol (1,6), diethylene glycol, triethylene glycol or tetraethylene glycol with diaryl carbonates, e.g. Diphenyl carbonate, or phosgene can be produced.

The polyester amides and polyamides include e.g. the predominantly linear condensates obtained from polyvalent saturated and unsaturated carboxylic acids or their anhydrides and polyvalent saturated and unsaturated amino alcohols, diamines, polyamines and their mixtures.

Polyhydroxyl compounds already containing urethane or urea groups and optionally modified natural polyols such as castor oil, carbohydrates or starch can also be used. Addition products of alkylene oxides with phenol-formaldehyde resins or with urea-formaldehyde resins can also be used in the process according to the invention.

Representatives of these compounds which can be used in the process according to the invention are e.g. in High Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology", written by Saunders-Frisch, Interscience Pubiishers, New York, London, volume 1.1962, pages 32-42 and pages 44-54 and

Volume II, 1964, pages 5-6 and 198-199, as well as in the plastics manual, Volume VII, Vieweg-Höchtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45-71.

Of course, mixtures of the above compounds with at least two isocyanate-reactive hydrogen atoms with a molecular weight of 400-10,000, e.g. Mixtures of polyethers and polyesters can also be used.

Compounds with at least two hydrogen atoms which are reactive towards isocyanates and have a molecular weight of 32-400 are also suitable as the initial components to be used in the process according to the invention, optionally in amounts of up to 50% by weight, based on the polyether. In this case too, this is usually understood to mean hydroxyl groups and / or amino groups and / or thiol groups and / or carboxyl groups, preferably hydroxyl and / or amino compounds which serve as chain extenders or crosslinking agents. These compounds generally have 2 to 8, preferably 2 or 3, hydrogen atoms which are reactive toward isocyanates.

Examples of such compounds are: ethylene glycol, propylene glycol (1,2) and - (1,3), butylene glycol (1,4) and - (2,3), pentanediol (1,5), Hexanediol- (1,6), octanediol- (1,8), neopentyl glycol, 1,4-bishydroxymethyl-cyclohexane, 2-methyl-1,3-propanediol, glycerol, trimethylolpropane, hexanetriol- (1,2,6), Trimethylolethane, pentaerythritol, quinite, mannitol and sorbitol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols with a molecular weight up to 400, dipropylene glycol, polypropylene glycols with a molecular weight up to 400, dibutylene glycol, polybutylene glycols with a molecular weight of up to 400, hydroxyethyl hydroquinone, ethanolamine, diethanolamine, triethanolamine, 3-aminoropropanol, ethylenediamine, 1,3-diamino-propane, l-mercapto-3-aminopropane, 4-hydroxy- or amino-phthalic acid, succinic acid, adipic acid,

Hydrazine, N, N'-dimethylhydrazine, 4,4'-diaminodiphenylmethane, toluenediamine, methylene-bis-chloroaniline, methylene-bis-anthranilic acid ester, diaminobenzoic acid ester and the isomeric chlorophenylene diamines. According to the invention, hydroxylalkylamines with terminal secondary and / or primary amino groups can preferably be used; In particular, the following compounds may be mentioned, for example:

N-methylamino-ethanol, N-methylamino-propanol, hydroxyalkylpiperazines such as e.g. Hydroxyethylpiperazine, 2- (methyl- (3-aminopropyl) amino) ethanol, 2-amino-2-methylpropanol, 4-hydroxybutyl-3-aminopropyl ether.

In this case too, mixtures of different compounds with at least two isocyanate-reactive hydrogen atoms with a molecular weight of 32-400 can be used.

According to the invention, polyhydroxyl compounds in which high molecular weight polyadducts or polycondensates are contained in finely dispersed or dissolved form can also be used in amounts of up to 50% by weight, based on the polyether. Modified polyhydroxyl compounds of this type can be obtained if polyaddition reactions (for example reactions between polyisocyanates and amino-functional compounds) or polycondensation reactions (for example between formaldehyde and phenols and / or amines) directly in situ in the abovementioned compounds containing hydroxyl groups expires. Such methods are described, for example, in German Patent Specifications 1 168 075 and 1 260 142, as well

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German Offenlegungsschriften 2 324 134.2 423 984, 2512 385.2513 815.2550 796.2 550 797.2 550 833 and 2 550 862. However, it is also possible, according to US Pat. No. 3,869,413 or German Offenlegungsschrift 2,550,860, to mix a finished aqueous polymer dispersion with a polyhydroxyl compound and then to remove the water from the mixture.

According to the invention, water and / or volatile organic substances are preferably used as blowing agents. As organic blowing agents come e.g. Acetone, ethyl acetate, halogen-substituted alkanes such as methylene chloride, chloroform, ethylidene chloride, vinylidene chloride, monofluorotrichloromethane, chlorodifluoromethane, dichlorodi-fluoromethane, butane, hexane, heptane or diethyl ether are also suitable. A blowing effect can also be achieved by adding compounds which decompose at temperatures above room temperature, with the elimination of gases, for example nitrogen. Azo compounds such as azoisobutyric acid nitrile can be achieved. Further examples of blowing agents as well as details on the use of blowing agents are in the plastic manual, Volume VII, published by Viewegund Höchtlen, Carl-Hanser-Verlag, Munich 1966, e.g. on pages 108 and 109, 453 to 455 and 507 to 510.

According to the invention, catalysts can also often be used. Suitable catalysts to be used include those of the type known per se, e.g. tertiary amines, such as triethylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, N-cocomorpholine, N, N, N ', N'-tetramethyl-ethylenediamine, 1,4-diaza-bicyclo- (2,2, 2) octane, N-methyl-N'-dimethylaminoethyl-piperazine, N, N-dimethylbenzylamine, bis (N, N-diethylaminoethyl) adipate, N, N-diethylbenzylamine, pentamethyldiethylene triamine, N, N-dimethylcyclohexylamine, N, N, N ', N'-tetra-methyl-1,3-butanediamine, N, N-dimenthyl-ß-phenylethylamine, 1,2-dimethylimidazole, 2-methylimidazole. Suitable catalysts are also known Mannich bases from secondary amines, such as dimethylamine, and aldehydes, preferably formaldehyde, or ketones such as acetone, methyl ethyl ketone or cyclohexanone and phenols, such as phenol, nonylphenol or bisphenol.

Preferred tertiary amines having isocyanate groups which have active hydrogen atoms as catalysts are e.g. Triethanolamine, triisopropanolamine, N-methyldi-ethanolamine, N-ethyl-diethanolamine, N, N-dimethyl-ethanolamine, and their reaction products with alkylene oxides, such as propylene oxide and / or ethylene oxide.

Silaamines with carbon-silicon bonds also come as catalysts, such as those e.g. in German Patent 1,229,290 (corresponding to American Patent 3,620,984) are in question, e.g. 2,2,4-trimethyl-2-silamorpholine and 1,3-diethylaminomethyl-tetramethyl-disiloxane.

Suitable catalysts are also nitrogen-containing bases such as tetraalkylammonium hydroxides, alkali metal hydroxides such as sodium hydroxide, alkali metal phenates such as sodium phenolate or alkali metal alcoholates such as sodium methylate. Hexahydrotriazines can also be used as catalysts.

According to the invention, organic metal compounds, in particular organic tin compounds, can also be used as catalysts.

Preferred organic tin compounds are tin (II) salts of carboxylic acids such as tin (II) acetate, tin (II) octoate, tin (II) ethylhexoate and tin (II) laurate and the tin (IV) compounds, e.g. Dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin di-laurate, dibutyltin maleate or dioctyltin diacetate in

Consider. Of course, all of the above catalysts can be used as mixtures.

Further representatives of catalysts to be used preferably in the process according to the invention and details of the mode of action of the catalysts are in the plastic handbook, volume VII, published by Vieweg and Höchtlen, Carl-Hanser-Verlag, Munich 1966, e.g. on pages 96 to 102.

The catalysts are generally used in an amount between about 0.001 and 10% by weight, based on the amount of polyethers to be used according to the invention, with a molecular weight of 400 to 10,000.

According to the invention, surface-active additives, such as emulsifiers and foam stabilizers, can optionally also be used. The emulsifiers are e.g. the sodium salts of castor oil sulfonates or salts of fatty acids with amines such as oleic acid diethylamine or stearic acid diethanolamine in question. Alkali metal or ammonium salts of sulfonic acids such as, for example, of dedecylbenzenesulfonic acid or dinaphthylmethane disulfonic acid or of fatty acids such as ricinoleic acid or of polymeric fatty acids can also be used as surface-active additives.

Polyether siloxanes, especially water-soluble representatives, are particularly suitable as foam stabilizers. These compounds are generally constructed in such a way that a copolymer of ethylene oxide and propylene oxide is linked to a polydimethylsiloxane radical. Such foam stabilizers are e.g. in U.S. Patent Nos. 2,834,748, 2,917,480 and 3,629,308.

However, it can also be advantageous to work in the absence of foam stabilizers of the polyether siloxane type.

According to the invention, reaction retarders, e.g. acidic substances, such as hydrochloric acid or organic acid halides, also cell regulators of the type known per se, such as paraffins or fatty alcohols or dimethylpolysiloxanes, as well as pigments or dyes and flame retardants of the type known per se, e.g. Tris-chloro-ethyl phosphate, tricresyl phosphate or ammonium phosphate and polyphosphate, also stabilizers against aging and weather influences, plasticizers and funistatic and bacteriostatic substances as well as fillers such as barium sulfate, diatomaceous earth, soot or sludge chalk are also used.

Further examples of surface-active additives and foam stabilizers, as well as cell regulators, reaction retarders, stabilizers, flame-retardant substances, plasticizers, dyes and fillers, as well as fungistatic and bacteriostatic substances, as well as details on the use and action of these additives, can be found in the Plastics Manual, Volume VII , published by Vieweg and Höchtlen, Carl-Hanser-Verlag, Munich 1966, eg described on pages 103 to 113.

According to the invention, the reaction components can be reacted by the one-step process known per se, the prepolymer process or the semi-prepolymer process, machine equipment often being used, e.g. those described in U.S. Patent 2,764,565. Details on processing devices that can also be used in the process according to the invention are given in the plastics manual, volume VII, published by Vieweg and Höchtlen, Carl-Hanser-Verlag, Munich 1966, e.g. described on pages 121 to 205.

Foam production preferably involves inventing

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according to the foaming often carried out in molds. The reaction mixture is usually entered in a form. Metal, e.g. Aluminum, or plastic, e.g. Epoxy resin, in question. The foamable reaction mixture foams in the mold and forms the shaped body. The molding can be carried out in such a way that the molded part has a cell structure on its surface, but it can also be carried out in such a way that the molded part has a compact skin and a cellular core. According to the invention, one can proceed in this context by adding so much foamable reaction mixture to the mold that the foam formed just fills the mold. However, it is also possible to work by adding more foamable reaction mixture to the mold than is necessary to fill the interior of the mold with foam. In the latter case, work is carried out under "overpacking"; such a procedure is e.g. known from U.S. Patents 3,178,490 and 3,182,104.

In the case of mold foaming, well-known "external release agents" such as silicone oils can often be used. However, it is also possible to use so-called “internal release agents”, optionally in a mixture with external release agents, such as those used, for example, have become known from German Offenlegungsschriften 2121670 and 2 307 589.

Of course, foams can also be produced by block foaming or by the double conveyor belt process known per se.

Cold-curing foams are obtained according to the invention (cf. British patent specification 1 162 517, German patent application specification 2153 086).

The products obtainable according to the invention find e.g. Use as upholstery materials.

example 1

(Comparative example)

A) 100 parts by weight of a polypropylene glycol started on trimethylolpropane and modified with ethylene oxide in such a way that 80% primary hydroxyl groups with an OH number of 28 result in the end,

3.2 parts by weight of water,

0.15 parts by weight of diazabicyclo-2,2,2-octane

0.10 parts by weight of 2,2 '-dimenthylaminodiethyl ether

5 parts by weight of trichlorofluoromethane and

B) 54.8 parts by weight of a polyisocyanate mixture consisting of

34% by weight of 2,4'-diphenylmethane diisocyanate, 51% by weight of 4,4'-diphenylmethane diisocyanate, 15% by weight of oligomeric polyphenylpolymethylene polyisocyanates were reacted with one another in a closed form.

De-molding time: 8 minutes

A flexible molded foam with the following mechanical properties is obtained:

Gross density DIN 53420 (kg / m3) 44

Tensile test DIN 53571 (KPa) 130

Elongation at break DIN 53571 (%) 150

Compression test DIN 53577 (KPa) 5.4

Example 2

A) 100 parts by weight of a polypropylene glycol started on trimethylolpropane and modified with ethylene oxide in such a way that 85% of the primary hydroxyl groups with an OH number of 28 result in the end,

2.7 parts by weight of water

0.33 parts by weight of diazabicyclo-2,2,2-octane

0.1 part by weight of 2,2'-dimethylaminodiethyl ether

0.5 part by weight of N-methylmorpholine

0.02 part by weight of dibutyltin dilaurate

1.5 parts by weight of glycerin

8 parts by weight of trichlorofluoromethane and

B) 54.0 parts by weight of a polyisocyanate mixture consisting of

5% by weight of 2,4'-diphenylmethane diisocyanate 80% by weight of 4,4'-diphenylmethane diisocyanate 15% by weight of oligomeric polyphenylpolymethylene polyisocyanates are reacted with one another in a closed form.

De-molding time: 1 minute

A flexible molded foam with the following mechanical properties is obtained:

Bulk density DIN 53420 (kg / m3) 43

Tensile test DIN 53571 (KPa) 105

Elongation at break DIN 53571 (%) 130

Compression test DIN 53577 (KPa) 5.8

Example 3

A) 100 parts by weight of a polypropylene glycol started on trimethylolpropane and modified with ethylene oxide in such a way that 75% primary hydroxyl groups with an OH number of 35 result in the end,

2.7 parts by weight of water,

0.33 parts by weight of diazabicyclo-2,2,2-octane

0.06 part by weight of 2,2'-dimethylaminodiethyl ether

0.5 part by weight of N-methylmorpholine

0.2 parts by weight of dibutyltin dilaurate

1.5 parts by weight of glycerin

8 parts by weight of trichlorofluoromethane and

B) 50.4 parts by weight of a polyisocyanate mixture consisting of

10% by weight of 2,4'-diphenylmethane diisocyanate 7 5% by weight of 4,4'-diphenylmethane diisocyanate 15% by weight of oligomeric polyphenylpolymethylene polyisocyanates, which contains 20% by weight of tolylene diisocyanate (2,4-: 2,6-isomer such as 80:20% by weight), are reacted with each other in a closed form.

A flexible molded foam with the following mechanical properties is obtained:

Demolding time: 1 minute 30 seconds

Gross density DIN 53420 (kg / m3) 42.5

Tensile test DIN 53571 (KPa) 85

Elongation at break DIN 53571 (%) 145

Compression test DIN 53577 (KPa) 4.7

Example 4

A) 100 parts by weight of a polypropylene glycol started on glycerol and modified with ethylene oxide in such a way that 80% primary hydroxyl groups with an OH number of 28 result in the end,

3.0 parts by weight of water,

0.55 parts by weight of diazabicyclo-2,2,2-octane

0.06 part by weight of 2,2'-dimethylaminodiethyl ether

5 parts by weight of trichlorofluoromethane and

B) 51.75 parts by weight of a polyisocyanate mixture consisting of

26% by weight 2,4'-diphenylmethane diisocyanate 64% by weight 4,4'-diphenylmethane diisocyanate

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10% by weight of oligomeric polyphenylpolymethylene polyisocyanates are reacted with one another in closed form.

A flexible molded foam with the following mechanical properties is obtained:

other reacted.

Demolding time: 2 minutes 30 seconds

A flexible molded foam with the following mechanical properties is obtained:

Bulk density tensile test elongation at break compression test

DIN 53420 (kg / m3) DIN 53571 (KPa) DIN 53571 (%) DIN 53577 (KPa)

56 Gross density 200 tensile test 185 elongation at break 6.8 io compression test

DIN 53420 (kg / m3) DIN 53571 (KPa) DIN 53571 (%) DIN 53577 (KPa)

51 205 215 5.4

Demolding time: 2 minutes 30 seconds

A free foam with the following mechanical properties is obtained with the same recipe:

Bulk density tensile test elongation at break compression test

DIN 53420 (kg / m3) DIN 53571 (KPa) DIN 53571 (%) DIN 53577 (KPa)

44 110 180 3.2

Example 7

Production of a flexible integral foam 95 parts by weight of a polypropylene glycol started on trimethylolpropane and modified with ethylene oxide in such a way that approximately 80% primary hydroxyl groups with an OH number of 28 result in the end,

Example 5

A) 100 parts by weight of a polypropylene glycol started on trimethylolpropane and modified with ethylene oxide in such a way that 80% primary hydroxyl groups with an OH number of 28 result in the end,

2.7 parts by weight of water,

0.20 parts by weight of diazabicyclo-2,2,2-octane

0.06 part by weight of 2,2'-dimethylaminodiethyl ether

5 parts by weight of trichlorofluoromethane and

B) 48.8 parts by weight of a polyisocyanate mixture consisting of

10% by weight of 2,4'-diphenylmethane diisocyanate 60% by weight of 4,4'-diphenylmethane diisocyanate 30% by weight of polyphenylpolymethylene polyisocyanate are reacted with one another in a closed form.

Demolding time: 2 minutes

A molded foam with the following mechanical properties is obtained:

5 parts by weight

0.4 parts by weight

0.35 parts by weight

0.5 parts by weight

8 parts by weight

20 ethylene glycol water

Diazabicyclo-2,2,2-octane tetramethylethylenediamine trichlorofluoromethane

25th

are mixed together. The mixture is then mixed with 28.0 parts by weight of a polyisocyanate mixture

30 2,4'-diphenylmethane diisocyanate (10 percent by weight) 4,4'-diphenylmethane diisocyanate (75 percent by weight) oligomeric polyphenylpolymethylene polyisocyanates (15 percent by weight)

35 Demolding time: 2 minutes

The reaction mixture is poured into a closed mold. Molded foam with integral skin (flexible integral foam) with the following properties:

40 Density Tensile strength Elongation at break Compression hardness

Bulk density tensile test elongation at break compression test

DIN 53420 (kg / m3) DIN 53571 (KPa) DIN 53571 (%) DIN 53577 (KPa)

43 80 105 3.8

DIN 53420 (kg / m3) DIN 53571 (KPa) DIN 53571 (%) DIN 53577 (KPa)

105 135 115 13.5

Example 6

A) 100 parts by weight of a polypropylene glycol started on trimethylolpropane and modified with ethylene oxide in such a way that 60% primary hydroxyl groups with an OH number of 28 result in the end,

3.0 parts by weight of water,

0.5 parts by weight of diazabicyclo-2,2,2-octane

0.06 part by weight of 2,2'-dimethylaminodiethyl ether

5 parts by weight of trichlorofluoromethane and

B) 51.75 parts by weight of a polyisocyanate mixture consisting of

26% by weight of 2,4'-diphenylmethane diisocyanate 69% by weight of 4,4'-diphenylmethane diisocyanate 5% by weight of oligomeric polyphenylpolymethylene polyisocyanates were included in a closed form.

45 By comparing Example 1 with Examples 2-6, the influence of the 2,4 '/ 4,4' isomer ratio and the two-core / multi-core ratio on the demolding time is demonstrated.

While a molded foam with a two-core content of about 85% by weight, based on the polyisocyanate mixture, and a 4,4'-diphenylmethane diisocyanate content of about 50% by weight, based on the polyisocyanate mixture, can be removed from the mold after 8 minutes (see Example 1), a molded foam can be removed from the mold after 1 minute with the same two-core fraction and with a 55,4'-diphenylmethane diisocyanate fraction of 75% by weight (see Example 2). The foams described in Example 2-6 cure so quickly that molded foams can be stacked and ready for dispatch on this basis after 1 hour, while the molded parts based on 60 of the previously known cold foam systems (see Example 1, for example) are ready for dispatch or assembly 24 Stored for hours or reheated at 120-150 ° C for 30-60 minutes in order to avoid irreversible deformations occurring under pressure.

B

Claims (5)

636364 PATENT CLAIMS 1. A process for the preparation of cold-curing, flexible, urethane group-containing foams by reacting at least two hydroxyl-containing polyethers with a molecular weight of 400-10000, in which at least 10% by weight of the hydroxyl groups present are primary hydroxyl groups and, if appropriate, in amounts of up to 50 Wt , With a mixture of diphenylmethane diisocyanates and oligomeric polyphenyl-polymethylene polyisocyanates, which additionally up to 20 wt .-%, based on the mixture of isocyanates, aliphatic, cycloaliphatic and from the aromatic isocyanates mentioned aromatic isocyanates and heterocyclic polyisocyanates and their mixtures n may contain, during the reaction optionally up to 50 wt .-%, based on the polyether, of 2 isocyanate-reactive compounds containing hydrogen atoms with a molecular weight of 32-400 are present in the presence of blowing agents, characterized in that the Mixture of diphenylmethane diisocyanates and oligomeric polyphenyl polymethylene polyisocyanates contains 60-90% by weight of 4,4'-diphenylmethane diisocyanate. 2. The method according to claim 1, characterized in that the reaction is carried out in the presence of catalysts and other foam auxiliaries. 3. The method according to claim 1, characterized in that the mixture of diphenylmgthane diisocyanates and oligomeric polyphenyl-polymethylene polyisocyanates contains 10-25% by weight, preferably 10-20% by weight, of 2,4'-diphenylmethane diisocyanate . 4. Process according to Claims 1 to 3, characterized in that the reaction is carried out in the absence of foam stabilizers of the polyether polysiloxane type. 5. The method according to claims 1 to 4, characterized in that foam molded parts are produced with integral skin. It is known that foams containing urethane groups are widely used, e.g. in the field of insulation, for the production of structural elements or for upholstery purposes. It is also known to use cold-curing foams made of higher molecular weight polyols, e.g. To produce hydroxyl-containing polyethers, polyisocyanates, water and / or other blowing agents, if appropriate in the presence of catalysts and other auxiliaries. Often at least two hydroxyl groups containing polyethers in which at least about 10% of the OH groups present are primary OH groups and which e.g. have a molecular weight of 400-10,000, e.g. in combination with the polyisocyanates. The polyisocyanate comes e.g. a mixture of diphenylmethane diisocyanates and oligomeric polyphenyl-poly-methylene-polyisocyanates. The previously known cold-curing foams based on a mixture of diphenylmethane diisocyanates and oligomeric polyphenyl polymethylene polyisocyanates naten, such as DT-OS 2 425 657 (Example 1 -5) describes the following serious disadvantage (which is particularly noticeable with molded foams): Even after demolding times of approx. 10 minutes, these foams can still be irreversibly deformed. This susceptibility to deformation can be overcome by storing it for approx. 24 hours or by subsequently heating the demolded foams (approx. 30 minutes / 120 ° C), but it remains disadvantageous in any case. Furthermore, according to DT-OS 2 425 657 it is not possible to achieve a mold life of less than 5 minutes. A process has now been found for the production of cold-curing, flexible foams containing urethane groups, which is based on the use of a certain mixture of diphenylmethane diisocyanates and oligomeric polyphenyl-polymethylene polyisocyanates, whereby the disadvantages described above are avoided.